无法接收来自某些域的电子邮件

几年来，我的电子邮件服务器一直运行良好，没有出现任何问题，但最近我遇到了两次在网站上注册却从未收到验证邮件的情况。一次来自mcsignup.com域名，另一次来自mandrillapp.com。

这是邮件日志文件中的一个示例条目：

postfix/smtpd[1550221]: connect from mail17.mcsignup.com[198.2.179.112]
postfix/smtpd[1550221]: discarding EHLO keywords: CHUNKING
postfix/smtpd[1550221]: disconnect from mail17.mcsignup.com[198.2.179.112] ehlo=1 starttls=1 quit=1 commands=3
postfix/smtpd[1550221]: connect from mail17.mcsignup.com[198.2.179.112]
postfix/smtpd[1550221]: discarding EHLO keywords: CHUNKING
postfix/smtpd[1550221]: disconnect from mail17.mcsignup.com[198.2.179.112] ehlo=1 starttls=1 quit=1 commands=3

我在另一篇文章中看到，这可能是由于我的某些设置过于严格，但我想在进行任何更改之前先了解问题所在。我正在运行 spamassassin，但我认为邮件甚至还没有到达那个阶段。

还有其他日志文件需要我检查吗？

如果我需要共享一些配置文件以使事情变得更容易，请告诉我。

[编辑] main.cf

alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
append_dot_mydomain = no
biff = no
home_mailbox = Maildir/
inet_interfaces = all
inet_protocols = ipv4, ipv6
local_recipient_maps = proxy:unix:passwd.byname $alias_maps
mailbox_size_limit = 0
mailbox_transport = lmtp:unix:private/dovecot-lmtp
message_size_limit = 33554432
milter_default_action = accept
milter_protocol = 2
mydestination = mail.marcocastorina.com, marcocastorina.com, localhost.localdomain, localhost
mydomain = marcocastorina.com
myhostname = mail.marcocastorina.com
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
myorigin = $mydomain
non_smtpd_milters = $smtpd_milters
readme_directory = no
recipient_delimiter = +
relayhost =
smtp_dns_support_level = dnssec
smtp_host_lookup = dns
smtp_tls_mandatory_protocols = >=TLSv1.2
smtp_tls_protocols = >=TLSv1.2
smtp_tls_security_level = dane
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU)
smtpd_discard_ehlo_keywords = chunking
smtpd_forbid_unauth_pipelining = yes
smtpd_milters = inet:localhost:12301
smtpd_recipient_restrictions = permit_mynetworks permit_sasl_authenticated reject_unauth_destination reject_unknown_sender_domain
smtpd_sasl_auth_enable = yes
smtpd_sasl_local_domain = $mydomain
smtpd_sasl_path = private/auth
smtpd_sasl_security_options = noanonymous
smtpd_sasl_type = dovecot
smtpd_sender_restrictions = permit_sasl_authenticated permit_mynetworks
smtpd_tls_CAfile = /etc/letsencrypt/live/mail.marcocastorina.com/fullchain.pem
smtpd_tls_cert_file = /etc/letsencrypt/live/mail.marcocastorina.com/cert.pem
smtpd_tls_key_file = /etc/letsencrypt/live/mail.marcocastorina.com/privkey.pem
smtpd_tls_mandatory_ciphers = high
smtpd_tls_mandatory_exclude_ciphers = aNULL, MD5
smtpd_tls_mandatory_protocols = >=TLSv1.2
smtpd_tls_protocols = >=TLSv1.2
smtpd_tls_security_level = encrypt
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache

主配置文件

smtp       inet  n       -       y       -       -       smtpd -o content_filter=spamassassin
submission inet  n       -       y       -       -       smtpd -o syslog_name=postfix/submission -o smtpd_tls_security_level=encrypt -o smtpd_sasl_auth_enable=yes -o smtpd_sasl_type=dovecot -o smtpd_sasl_path=private/auth -o smtpd_client_restrictions=permit_sasl_authenticated,reject -o smtpd_recipient_restrictions=reject_non_fqdn_recipient,reject_unknown_recipient_domain,permit_sasl_authenticated,reject_unauth_destination,reject
pickup     unix  n       -       y       60      1       pickup
cleanup    unix  n       -       y       -       0       cleanup
qmgr       unix  n       -       n       300     1       qmgr
tlsmgr     unix  -       -       y       1000?   1       tlsmgr
rewrite    unix  -       -       y       -       -       trivial-rewrite
bounce     unix  -       -       y       -       0       bounce
defer      unix  -       -       y       -       0       bounce
trace      unix  -       -       y       -       0       bounce
verify     unix  -       -       y       -       1       verify
flush      unix  n       -       y       1000?   0       flush
proxymap   unix  -       -       n       -       -       proxymap
proxywrite unix  -       -       n       -       1       proxymap
smtp       unix  -       -       y       -       -       smtp
relay      unix  -       -       y       -       -       smtp
showq      unix  n       -       y       -       -       showq
error      unix  -       -       y       -       -       error
retry      unix  -       -       y       -       -       error
discard    unix  -       -       y       -       -       discard
local      unix  -       n       n       -       -       local
virtual    unix  -       n       n       -       -       virtual
lmtp       unix  -       -       y       -       -       lmtp
anvil      unix  -       -       y       -       1       anvil
scache     unix  -       -       y       -       1       scache
maildrop   unix  -       n       n       -       -       pipe flags=DRhu user=vmail argv=/usr/bin/maildrop -d ${recipient}
uucp       unix  -       n       n       -       -       pipe flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)
ifmail     unix  -       n       n       -       -       pipe flags=F user=ftn argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient)
bsmtp      unix  -       n       n       -       -       pipe flags=Fq. user=bsmtp argv=/usr/lib/bsmtp/bsmtp -t$nexthop -f$sender $recipient
scalemail-backend unix - n       n       -       2       pipe flags=R user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store ${nexthop} ${user} ${extension}
mailman    unix  -       n       n       -       -       pipe flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py ${nexthop} ${user}
spamassassin unix -      n       n       -       -       pipe user=debian-spamd argv=/usr/bin/spamc -f -e /usr/sbin/sendmail -oi -f ${sender} ${recipient}